He therefore that despiseth, despiseth not man, but God, who hath also given unto us his holy Spirit. He therefore that despiseth - He who will not receive these teachings, and is led either to undervalue or despise them, despises not us but God, from whom we have received our commission, and by whose Spirit we give these directions. See Clarke's note on 1 Thessalonians 4:15.
Hath also given unto us his Holy Spirit - Instead of εις ἡμας, unto Us, εις ὑμας, unto You, is the reading of BDEFG, a great many others, the Syriac, all the Arabic, Armenian, later Syriac in the margin, some of the Itala, Clement, Didymus, and Ambrosiaster; this seems to be the better reading. God has taught us that we may teach you; and he has also given you his Holy Spirit that ye might understand and be enabled to practice these things. It is one thing to receive a revelation from the Spirit of God; it is another thing to receive that Spirit to enable a man to live according to that revelation. In the first sense the apostles alone received this Holy Spirit; in the latter sense all true Christians, as well as the Thessalonians, receive it. I think ὑμας, you, is the true reading, and that it is confirmed by the following verse: For ye yourselves are Taught of God to love one another. Griesbach has inserted it in the margin, but has not admitted it into the text, because it has not what he deemed full support from those MSS. which are of the Alexandrian recension; but he thought its genuineness very probable.